GULLIVER. — SHORELINE TOPOGRAPHY. 191 



Sable Island, composed of unconsolidated materials, is rapidly disappearing. * 

 The map shows an enclosed lagoon, which was formerly nearly twice its present 

 length. t Its form and structure suggest that it represents a flying-bar, after the 

 island, from which its materials were derived, had been completely destroyed. 



Simple Cases of Island-tying and their Stages. — One of the features of 

 shore development following depression which shows in most clear and 

 decisive terms the relative time since depression, is the formation of tom- 

 bolos connecting islands with each other and with the mainland. When 

 the sea is able to do the work given it to perform, shore-grade is estab- 

 lished and littoral transportation occurs along the base of the cliffs, which 

 are cut on the more exposed portions of the island and mainland, and 

 deposition begins along the edge of the currents in the comparatively 

 dead water. Such dead water naturally occurs upon the protected side 

 of the island between it and the mainland, and a tombolo is begun usually 

 upon that side. According to the direction of transportation the bar 

 may grow from the island, from the headland, or from them both. The 

 essential point to bear in mind is this : the currents will seek to alter the 

 shoreline better to satisfy their conditions of work. 



Numerous examples from various localities are given of the seven 

 stages into which island-tying has been divided. The lists under this 

 and other headings of the present article are however not at all exhaus- 

 tive, enough examples being given in each case to bring out the successive 

 stages of development and to show the play of the variable elements 

 within the limits of each stage. 



I. Initial Island (Birth) : Austria ; Sweden. — Tlie fii-st stage in the 

 life of an island is where no work whatever has been done upon it by 

 the sea. Great variety of form and size will occur, depending largely 

 upon internal structure and pre-natal development. The longitudinal 

 structure of Austria, the transverse structure of Casco bay (Figure 1), 

 and the concentric structure shown on the Vaxholm sheet of Sweden, 

 give markedly different island forms. The mature dissection of Scan- 

 dinavia gives many small islands, while the more youthful dissection in 

 the Puget sound region shows but few islands, and these much larger. 



II. Nipped Island (Iniancy) : Sweden; Maine, Figure 1. — The sea 

 first attacks the coast and makes a nip all around the island, but cuts 

 more upon the exposed side. The sea at first can dispose of all the 

 waste from the island. 



* Patterson, Trans. Roy. Soc. Can., 1894, XII. (2) 1-50. Map. 

 t Loc. cit., p. 37. 



